The present invention relates to a method and apparatus for inducing artificial oceanographic upwelling and, in particular, to conducting a relatively fresh water stream to a predetermined depth so as to form a mixture with ambient sea water, and conducting the mixture from the depth.
Typically, the ocean is comprised of a plurality of discrete layers such that the upper surface layer has a relatively high temperature and salinity, while lower layers, often at depths of 1000 meters or more, have a relatively low temperature and salinity.
The ocean also exhibits a photic zone and an aphotic zone. The photic zone is defined by the depths of the ocean in which photosynthesis is capable of occurring. Typically, the necessary amount of sunlight required to carry on photosynthesis extends only 100 to 200 meters below the surface. As photosynthesis is the initial link in the food chain, the photic zone includes a host of nutrient-depleting life forms. These life forms substantially reduce the available nutrients of the photic zone.
The depth below the photic zone, where insufficient light penetrates to support photosynthesis, is known as the aphotic zone. The lack of nutrient depleting life forms combined with enrichment from the decay of organisms in the aphotic zone results in the deep water being, on the average, substantially richer in nutrients than the upper layers of the ocean. The existence of discrete ocean layers having distinct temperatures, densities, salinities and nutrient contents represents a substantial source of energy.
In an effort to utilize the potential energy stored within the ocean structure, attempts have been made to bring the relatively deep, nutrient-rich cold water towards the surface. The upwelling, or bringing towards the surface, of the cold, nutrient-rich water of the deep ocean provides for a variety of applications, including ocean thermal energy conversion (OTEC) systems and mariculture.
In the OTEC systems, warm surface water is used to vaporize a working fluid. In a closed loop OTEC system, the upwelled cold, deep water is brought to the surface to recondense the vaporized working fluid of the OTEC system. The upwelled water thereby provides the necessary heat sink for operation of the closed loop OTEC system.
In maricultural applications, the nutrient-rich water from the aphotic zone is brought to the photic zone, where phytoplankton utilize the nutrients in a photosynthetic process, thereby further creating the primary food source. The fish of the photic zone feed upon the increased food supply provided by the upwelled water. As the fish remain in the food-rich area of the upwelled water, the harvesting of the feeding fish is an efficient and economical process.
There have been many attempts to provide an economically viable means for generating artificial upwelling in the sea. The patent to Johnson (U.S. Pat. No. 4,597,360) discloses a salinity-driven oceanographic upwelling device designed to provide a continuous exchange of surface water and deep water. However, the Johnson device requires a main duct and a plurality of elongated flow-segregating members supported within the interior space of the main duct. The organization and retention of these ducts requires alignment of an extensive number of components, which increases the cost of the systems.
Breit U.S. Pat. No. 4,051,810 discloses an apparatus for utilizing deep ocean nutrients in which a wave motion pump floating at the surface of the ocean is utilized to pump warm surface waters downwardly through a down pipe which is positioned within a larger up pipe. The warming of the colder water together with a jet pump action created by a small diameter outlet on the bottom of the down pipe cause the nutrient-rich wastes to flow upwardly through the up pipe into the photic zone. In addition, it is briefly mentioned that "Supplemental waters are available from inland reservoirs under a head of pressure to be used directly, or as effluent from processing plants, and introduced by said lift means . . . " to impart vertical momentum of nutrient-rich deep ocean water. Thus, the lift means for the land water is the apparatus illustrated for the ocean water system. Such system is impractical for the inland water situation.
Therefore, a need exists for a relatively simple apparatus and method for inducing artificial upwelling in the ocean. A need also exists for a method of inducing upwelling which does not require an extensive apparatus. A further need exists for a method which creates artificial upwelling while employing currently available technology.